共查询到19条相似文献，搜索用时 671 毫秒
1.
The effectiveness of vitamin C in treating Cr(Ⅵ)-contaminated water is being evaluated. Cr(Ⅵ) is an identified pollutant of some soils and groundwater. Vitamin C, an important biological reductant in humans and animals, can be used to transform Cr(Ⅵ) to essentially nontoxic Cr(Ⅲ). The removal efficiency was 89% when the mass concentration of vitamin C was 80 mg/L in 60 min, and nearly 100% Cr(Ⅵ) was removed when the mass concentration was 100 mg/L. Our data demonstrated that the removal efficiency was affected by vitamin C concentration, the reaction temperature and the dissolved oxygen concentration.The reaction mechanism of Cr(Ⅵ) by vitamin C was presented. Our study opens the way to use vitamin C to remediate Cr(Ⅵ)-contaminated soils and groundwater. 相似文献
2.
Groundwater remediation by nanoparticles has收稿日期increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe0) nanoparticles. Cr(Ⅵ) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(Ⅵ), is an option in the remediation of contaminated sites, transforming Cr(Ⅵ) to essentially nontoxic Cr(Ⅲ). At a dose of 0.4 g/L, 100% of Cr(Ⅵ) (20 mg/L) was degraded. The Cr(Ⅵ) removal efficiency decreased significantly with increasing initial pH. Different Fe0 type was compared in the same conditions. The reactivity was in the order starch-stabilized Fe0 nanoparticles＞Fe0 nanoparticles＞Fe0 powder＞Fe0 filings. Electrochemical analysis of the reaction process led to the conclusion that Cr(OH)3 should be the final product of Cr(Ⅵ). Iron nanoparticles are good choice for the remediation of heavy metals in groundwater. 相似文献
3.
《天津大学学报(英文版)》2019,(6)
Cr(Ⅵ) and phenol are toxic contaminants that need to be treated,and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater.In this study,Cr(Ⅵ) was used as a novel Fenton-like catalyst in phenol degradation by H_2O_2.In the pH range of 3.0-11.0,the degradation efficiency of phenol decreased with elevated pH.At pH=3.0,100 mg/L phenol was effectively degraded by 2 mmol/L Cr(Ⅵ) and 20 mmol/L H_2O_2.At pH=7.0 and the same conditions as those of pH=3.0,79%of 100 mg/L phenol was removed within 6 h,which was an improvement in pH limitation compared with the Fe(Ⅱ)-mediated Fenton reaction.Quenching experiments indicated that'OH generated from the catalysis of H_2O_2 by Cr(Ⅴ) instead of Cr(Ⅵ) was the primary oxidant that degraded phenol.When pyrophosphate was added in the Cr(Ⅵ)/H_2O_2 system,complexes with the Cr(Ⅴ) intermediate rapidly formed and inhibited H_2O_2 decomposition,implying that the decomposition of H_2O_2 to'OH was catalyzed by Cr(Ⅴ) instead of Cr(Ⅵ).The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol.TOC and UV analyses suggest that phenol could not be completely oxidized to CO_2 and H_2O,and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids,primarily maleic,formic,acetic,and oxalic acids,and eventually into CO_2 and H_2O.Considering that more than 50%Cr(Ⅵ) can also be removed during this process,the Cr(Ⅵ)/H_2O_2 system is more appropriate for the simultaneous removal of Cr(Ⅵ) and phenol contaminants from industrial wastewater. 相似文献
4.
CAI Jing ZHENG Ping MAHMOOD Qaisar ISLAM Ejazul HU Bao-lan WU Dong-lei 《浙江大学学报(A卷英文版)》2007,8(7):1149-1156
The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (HRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed HRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter HRT but careful operation is needed. Nitrate conversion was more sensitive to HRT than sulfide conversion since the process performance deteriorated abruptly when HRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil. 相似文献
5.
Decomposition of dimethyl sulfide （DMS） in air was investigated experimentally by using a wire-cylinder dielectric barrier discharge （DBD） reactor at room temperature and atmospheric pressure. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse-forming network （BPFN） was adopted in our experiments. The maximum power output of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV, respectively. The important parameters affecting odor decomposition, including peak voltage, pulse frequency, gas flow rate, initial concentration, and humidity, which influenced the removal efficiency, were investigated. The results showed that DMS could be treated effectively and almost a 100% removal efficiency was achieved at the conditions with an initial concentration of 832 mg/m3 and a gas flow rate of 1000 ml/min. Humidity boosts the removal efficiency and improves the energy yield （EY） greatly. The EY of 832 mg/m3 DMS was 2.87 mg/kJ when the relative humidity was above 30%. In the case of DMS removal, the ozone and nitrogen oxides were observed in the exhaust gas. The carbon and sulfur elements of DMS were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, sulfur was discovered in the reactor. According to the results, the optimization design for the reactor and the matching of high pulse voltage source can be reckoned. 相似文献
6.
The use of a biotrickling filter was investigated for a pilot field-scale elimination of NH3 gas and other odorous gases from a composting plant in Tongzhou District, Beijing. The inlet gas flow rate was 3500 m3/h and NH3 concentration fluctuated between 2.76–27.84 mg/m3, while the average outlet concentration was 1.06 mg/m3 with an average of 94.9% removal. Critical volumetric loading (removal efficiency=100%) was 11.22 g-N/(m3·h). The odor concentration removal was 86.7%. NH3 removal efficiency decreased as the free ammonia (FA) in the trickling liquid increased. The pressure drop was maintained at about 50 Pa/m and was never more than 55 Pa/m. During the experiment, there was neither backflushing required nor any indication of clogging. Overall, the biotrickling filter was highly efficient and cost-effective for the simultaneous biodegradation of NH3 and other odorous gases from composting, suggesting the possibility of treating odorous gases at the industrial level. 相似文献
7.
Urban wastewater treatment techniques could not be applied to improve the pollutant removal efficiency,due to its characteristics of closed and quiescent conditions of the static lake water.In this study,natural zeolite and coal cinder were chosen as filler compounds of the ecological filter.Static and dynamic experiments were carried out to study the remediation efficiency.Experimental data show that removal efficiency of ammonia nitrogen （NH ＋ 4 -N） reaches 85% in both static and dynamic patterns and its removal efficiency reaches 97% when the recycling period is 1 h in dynamic condition.The maximum removal efficiency of nitrite nitrogen （NO-2 -N） reached 98%,and the removal efficiency of total nitrogen （TN） is a maximum of 84%.The final effluent concentration of total phosphorus （TP） is 0.079 mg/L.Effluent recycling could improve the nutrient （N,P） removal efficiently.Dissolved oxygen （DO） concentration could remain high with the water cycling.The filter works efficiently on regulating pH to the standard level of healthy water. 相似文献
8.
Hg0 absorption in potassium persulfate solution 总被引：1，自引：0，他引：1
The aqueous phase oxidation of gaseous elemental mercury （Hg^0） by potassium persulfate （KPS） catalyzed by Ag^＋ was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption （CVAA） and ion chromatograph （IC）, respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate （SN）, temperature, Hg^0 concentration in the reactor inlet and tertiary butanol （TBA）, free radical scavenger, on the removal efficiency of Hg^0 were studied. The results showed that the removal efficiency of Hg^0 increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg^0 was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO3. High Hg^0 concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed. 相似文献
9.
《天津大学学报(英文版)》2017,(4)
Biochar is a potential carrier for nutrients due to its porous nature and abundant functional groups. However, raw biochar has a limited or even negative capacity to adsorb phosphate. To enhance phosphate removal and reduce phosphate releases, acidic, alkaline, and surfactant pretreatments,followed by granulation and ferric oxide loading, were applied to raw biochar powder(B_p). The alkaline pretreatment proved to be the most effective method and exhibited significant pore expansion and surface oxidation. B_g-OH-FO showed the highest phosphate removal efficiency at 99.2%(initial phosphate concentration of 20 mg/L) after granulation and ferric oxide loading. Static adsorption results indicated that a p H value of 4 was the most suitable for phosphate adsorption because of the surface properties of B_g-OH-FO and the distribution of P(V) in water. Higher temperatures and a larger initial phosphate concentration led to better adsorption; the adsorption capacity of B_g-OH-FO was 1.91 mg/g at 313 K with an initial phosphate concentration of 50 mg/L. The B_gOH-FO adsorption process was endothermic in nature. The Freundlich model seemed to be the optimum isotherm model for B_g-OH-FO. Under continuous adsorption, the flow rate and bed depth were changed to optimize the operation conditions. The results indicate that a slow flow rate and high bed depth helped increase the removal efficiency(g) of the fixed bed. The breakthrough curves fitted well with the Yoon–Nelson model. 相似文献
10.
An improved configuration of the membrane stack was adopted in the electrodeionization （EDI） cell to prevent precipitation of bivalent metal hydroxide during the running. The operational parameters that influenced the removal of copper ions from the dilute solution were optimized. The result showed that a moderate decrease in the inlet pH value and a moderate increase in the applied voltage could achieve a better removal effect. The steady process of electroplating wastewater treatment could be achieved with a removal efficiency of more than 99.5% and an enrichment factor of 5-14. The concentration of copper in purified water was less than 0.23 mg/L. This demonstrated the applicability of recovering heavy metal ions and purified water from electroplating effluent for industrial reuse. 相似文献
11.
INTRODUCTION Chromium is a commonly identified soils andgroundwater contaminant. Cr(VI) is toxic, carcino-genic, and has great subsurface mobility. In contrast,Cr(III) is relatively non-toxic and immobile. Muchresearch focused on the remediation of Cr(VI) such asadsorption by zeolites (Bowman, 2003) or silicas(Hideaki et al., 2002), chemical reduction by ferrousiron (Buerge and Hug, 1999; Fendorf and Li, 1996) orzero-valent iron (Powell and Puls, 1997; Alowitz andScherer, 2002), b… 相似文献
12.
张志刚 《福建工程学院学报》2014,(6):557-561
采用柚子皮制备生物吸附剂用于去除水中的Cr(VI),考察了p H值、柚子皮投加量、柚子皮粒径、溶液离子强度、反应温度等因素对吸附效果的影响。结果表明,当溶液中Cr(VI)离子初始浓度15mg/L、p H 1.5、反应温度25℃、柚子皮投加量1.0g/100 m L、吸附时间7 h时,Cr(VI)离子去除率可达90%以上。柚子皮对Cr(VI)离子的吸附过程可以用Langmuir和Freundlich吸附等温模型来描述,吸附等温线线性相关性均较显著,吸附过程符合准二级动力学方程。柚子皮对水中Cr(VI)离子吸附性能较好,且运行成本低,可推广应用于水中重金属离子的治理。 相似文献
13.
14.
Removal of chromium (VI) dissolved in water by intermittent foam separation was implemented with cetyl trimethy-ammonium bromide
as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has
a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to
confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration
is 10 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal
efficiency of chromium (VI) reaches 97.80%, and condense multiple reaches 1 711. The kinetic test indicates that the foam
separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the
equivalent rate equation is obtained. 相似文献
15.
Cr(VI) and phenol are toxic contaminants that need to be treated, and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater. In this study, Cr(VI) was used as a novel Fenton-like catalyst in phenol degradation by H2O2. In the pH range of 3.0‒11.0, the degradation efficiency of phenol decreased with elevated pH. At pH = 3.0, 100 mg/L phenol was effectively degraded by 2 mmol/L Cr(VI) and 20 mmol/L H2O2. At pH = 7.0 and the same conditions as those of pH = 3.0, 79% of 100 mg/L phenol was removed within 6 h, which was an improvement in pH limitation compared with the Fe(II)-mediated Fenton reaction. Quenching experiments indicated that ·OH generated from the catalysis of H2O2 by Cr(V) instead of Cr(VI) was the primary oxidant that degraded phenol. When pyrophosphate was added in the Cr(VI)/H2O2 system, complexes with the Cr(V) intermediate rapidly formed and inhibited H2O2 decomposition, implying that the decomposition of H2O2 to ·OH was catalyzed by Cr(V) instead of Cr(VI). The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol. TOC and UV analyses suggest that phenol could not be completely oxidized to CO2 and H2O, and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids, primarily maleic, formic, acetic, and oxalic acids, and eventually into CO2 and H2O. Considering that more than 50% Cr(VI) can also be removed during this process, the Cr(VI)/H2O2 system is more appropriate for the simultaneous removal of Cr(VI) and phenol contaminants from industrial wastewater.
相似文献16.
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ａｑｕｅｏｕｓｅｆｆｌｕｅｎｔｓｄｉｓｃｈａｒｇｉｎｇｆｒｏｍｍｉｎｉｎｇａｎｄｏｔｈ ｅｒｉｎｄｕｓｔｒｉｅｓｃｏｎｔａｉｎｈｅａｖｙｍｅｔａｌｓｓｕｃｈａｓｌｅａｄ ,ｃａｄ ｍｉｕｍａｎｄｃｈｒｏｍｉｕｍｉｎｄｉｓｓｏｌｖｅｄａｎｄ ｐａｒｔｉｃｕｌａｔｅｆｏｒｍｓ[1] .Ｔｈｅｉｍｐａｃｔｏｆｕｎｔｒｅａｔｅｄｉｎｄｕｓｔｒｉａｌｅｆｆｌｕｅｎｔｓｏｎｔｈｅａｑｕｅｏｕｓｅｎｖｉｒｏｎｍｅｎｔｈａｓｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｓｔｕｄｉｅｄ[2 ] .Ｃｏｎｖｅｎｔｉｏ… 相似文献
17.
利用低温炭化法来制备柚子皮活性炭吸附剂。探讨了吸附剂用量、温度、pH值、Cr（Ⅵ）初始浓度、吸附时间等对吸附效果的影响。柚子皮吸附剂吸附处理Cr（Ⅵ）的最佳工艺条件是：吸附剂用量10g/L,温度40℃,pH=4,吸附时间10h,Cr（Ⅵ）初始浓度为100mg/L时,Cr（Ⅵ）的去除率能达到98%以上。柚子皮吸附剂对Cr（Ⅵ）具有良好的吸附能力,吸附过程符合二级吸附动力学模型并且可用Langmuir吸附等温线来描述。 相似文献
18.
实验室含铬废液处理方法的对比研究 总被引：2，自引：0，他引：2
实验室含铬废液不能直接排放,必须进行回收处理。采用化学还原法处理含Cr（VI）废液,对比研究了以亚硫酸钠、亚硫酸氢钠、抗坏血酸、硫酸亚铁为还原剂还原Cr（VI）的酸度条件、还原剂用量、反应时间等影响因素．结果表明：在最佳参件下,四种还原剂处理含Cr（VI）废液的去除率都在99．9％以上,处理后出水的Cr（VD浓度分别为0．048mg·L^-1、0．018mg·L^-1,0．038mg·L^-1,0．018mg·L^-1,均小于0．5mg·L^-1,达到了国家排放标准,取得了良好的处理效果。综合分析Cr（VI）~除率和经济效益得出亚硫酸氢钠为最佳还原剂。 相似文献
19.
A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and CODCr of wastewater was about 140 mg/L, it took 4 h to decrease the Cr^6 concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr^6 concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr^6 concentration reached 95.47 rag/L, the treatment time was prolonged to 7.5 h. Compared with the contrast system, the system with trace metals showed clear superiority in that the Cr^6 removal rate increased by 21.26%. Some analyses also showed that hexavalent chromium could probably be bio-reduced to trivalent chromium, and that as a result, the chrome hydroxide sediment was formed on the surface of microorganisms. 相似文献